Then he's going to fit right in with this horrible movie.
Seriously though, I think he's a fine choice physically. He'll need blonde hair and they'll probably go with the long-haired, bearded version of Arthur (which I find to be badass).
This movie is going to be an absolute clusterfuck. DC is desperately trying to catch up to Marvel in the cinematic universe and they're rushing things. This movie went from being Man of Steel 2, to Superman vs Batman.....to basically a Justice League movie. I have zero faith.
Keep in mind, I love DC and prefer the characters over Marvel, but aside from the Dark Knight trilogy, DC movies have been awful. Their cartoons are fucking amazing, though. I just watched Son of Batman recently and loved it.
So yeah...this movie will suck but I will see it. Aquaman is a badass, so I'm hoping he's at least portrayed as such in this movie.